This application is a revision of my previous grant application, 1 R03 EY014405. The development of neural pathways in vertebrates requires the delivery and exchange of trophic signals between neuronal populations. Important trophic signals are transported anterogradely along axons, presumably mediated by kinesin motors, to mediate the survival and differentiation of target cells. Loss of proper motor kinesin function and the resulting impairment of axonal transport cause several degenerative diseases in the peripheral and central nervous system. Members of the neurotrophin family of neurotrophic factors are transported anterogradely along axons of retinal ganglion cells (RGC) and other types of neurons, yet the molecular components of the transport machinery have not been identified. It is not known how neurotrophins are targeted to specific pathways and how they are delivered to specific domains within neurons. The proposed project focuses on the molecular analysis of anterograde transport of neurotrophin-3 (NT-3) in RGC neurons. This work will utilize a particularly advantageous system the retinotectal pathway of embryonic chickens, because bulk anterograde transport as well as anterograde transport of specific neurotrophins can be easily quantified in this system, and chicken RGC can be purified to 100% for subsequent molecular analysis. Experiments were designed to identify which motor kinesins are expressed in RGCs and to identify among them those kinesin(s) that are involved in transport of NT-3. Results of this proposal are expected to answer the following basic neuroscience questions: (1) How many different kinesins are expressed in one type of neuron, the RGC? (2) How will inhibition of specific kinesins in RGC affect bulk anterograde axonal transport in these cells? (3) Which kinesins mediate anterograde axonal transport of NT-3 and its receptors, p75 and trkC, in RGC? Knowledge of the molecular mechanisms of neurotrophin transport and targeting will significantly enhance our understanding of neurotrophin trafficking, sorting and signaling. The broader impact of the proposed work is to lay the foundation for future experimental work aimed at the selective manipulation of efficiency of axonal transport of Neurotrophins not only within the visual system, but in the entire nervous system.